Geophysics applies the principles of physics to the study of the Earth. It deals with such things as the movement of the Earth's crust and the temperatures of its interior. Another subject is the behavior of the still-mysterious geomagnetic field. Some geophysicists seek out deposits of ores or petroleum; others specialize in earthquakes; still others study the water beneath the Earth's surface, where it collects and how it flows.
Dr. Gary A. Glatzmaier - Los Alamos National Laboratory - U.S. Department of Energy.